Date: 27 Sep 1995
From: Oliver Kellogg
To: Jaap van Ganswijk
Subject: Re: Chip Directory
>Interesting, I can't remember having heard of them before...
>They are quite expensive, I guess. Or are there also commercial versions?
>Can you explain what the 'MIL-STD-1750 family of processors' is?
This is definitely a very-special-purpose chip. I think the total number of
users can't be more than a couple dozen people. There are no commercial
(non radiation-hardened) versions, and AFAIK prices start at US$ 5000
per chip.
I am appending some info on the 1750 architecture.
Cheers,
Oliver
--
The MIL-STD-1750 is a microprocessor architecture standard (by the
U.S. Air Force.) The standard encompasses not only the instruction
set, but also things such as floating-point formats and operations,
interrupt structure, I/O calls, and hardware signals.
The 1750 is a 16-bit architecture. In its basic layout, the processor
can only address 64k 16-bit words. The instruction set is somewhere
between RISC and CISC, and has been designed with special regard
to hard real-time applications. An MMU for addressing up to 1 Mwords
is optional, but it functions non-transparently (i.e. requires explicit
programming for page changes.)
Address counting is a bit unusual on the 1750: the unit of address is
16 bits, thus "addr+1" is 16 bits above "addr". In other words, it is
not possible to address bytes. (However, there exist special instructions
for Load/Store Upper/Lower Byte from a 16-bit word. )
The peculiarity about the MIL-STD-1750 is that most of its chip implement-
ations are manufactured to endure cosmic radiation and radioactivity. These
chips are therefore used mainly in military and space projects, and nuclear
power plants. Examples of implementations are: McDonnell-Douglas MDC281,
Fairchild F9450, IBM GVSC, Performance Semiconductor PACE, Marconi 31750.